Researchers are launching tests aimed at setting up a huge floating barrier off the Japanese coast, a project that could eventually help remove some of the 5.25 trillion pieces of rubbish polluting the world's oceans, officials ...

The enormous amount of press that Tesla received last month over the announcement of its battery storage system – the Powerwall – cannot be put down to just clever marketing. There are so many reasons why it has grabbed ...

Materials melt faster when the lines of heat spread through the cold material like the branches of a tree—and the melting rate can be steadily increased by allowing the tree architecture to freely evolve over time, researchers ...

Andre Borschberg and Bertrand Piccard have suffered set-backs in their quest to circumnavigate the earth in an experimental solar-powered aircraft. The Swiss nationals are flying Solar Impulse 2, whose large fixed wing is ...

A space-based system that relies on lasers to generate and deliver energy to spacecraft has won a University of Alabama in Huntsville (UAH) professor a U.S. patent and could become a first-line defense against asteroids on ...

Raising healthy chicks is always a challenge, but in a cold, fish-free Arctic lake, it's an enormous undertaking. Red-throated Loon (Gavia stellata) parents must constantly fly back and forth between their nesting lakes and ...

Researchers at the University of Illinois at Urbana-Champaign have uncovered physical mechanisms allowing the manipulation of magnetic information with heat. These new phenomena rely on the transport of thermal energy, in ...

A fully renewable energy system, including all energy consuming sectors, is not only a possible but a viable solution for Finland, according to a new research. Researchers from Lappeenranta University of Technology (LUT) ...

Energy

In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working") is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law. Different forms of energy include kinetic, potential, thermal, gravitational, sound, light, elastic, and electromagnetic energy. The forms of energy are often named after a related force.

Any form of energy can be transformed into another form, but the total energy always remains the same. This principle, the conservation of energy, was first postulated in the early 19th century, and applies to any isolated system. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.

Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy relative to the Earth.